The main objective of this proposal is to evaluate the effectiveness of an innovative Interviewing strategy for the collection of self-report drug use information. This administration style, referred to as interactive thinkaloud interviewing, Is grounded in current understandings of the cognitive processes that underlie responses to survey questions. This interview format will provide interviewers with a set of skills and techniques designed to aid respondent comprehension, recall and judgment formation while minimizing response editing. It is hypothesized that this interview format will significantly improve both the reporting and accuracy of drug use. A sample of approximately 600 ethnically diverse adults in the City of Chicago between the ages of 18-34 will be interviewed face-to-face. Using random assignment, one-half will be interviewed using the interactive thinkaloud format. The remaining interviews would be conducted using standard National Household Survey on Drug Abuse procedures, which are considered state-of-the-art and the control condition against which innovations must be measured. In addition, this study will also evaluate the feasibility and acceptability of the collection of hair specimens for validation of survey responses in a general population. Based upon findings, recommendations with respect to the improvement of survey research procedures for the epidemiological assessment of drug use in the general population will be made.